In current telecommunications networks, radio resources and bandwidth resources are typically limited. Continually increasing number of mobile terminals and increasing access needs increase the importance of keeping a user equipment steadily connected under coverage (for example Long Term Evolution (LTE) coverage), especially in situations of relatively high network load in the core network which may be caused by control signaling and other data exchanges between the network elements of the telecommunications network.
Typically, overload protection mechanisms are employed to reduce the network load and provide reliable Internet Protocol (IP) services to the user equipments and its applications. Such overload protection mechanisms may be realized by throttling low priority data traffic (i.e. transmission of Internet Protocol (IP) data packets across the telecommunications network) in order to reduce the network load. Specifically, a mobility management entity (MME) overload protection mechanism includes the reduction of data traffic involving the mobility management entity. In order to forward Internet Protocol (IP) data packets directed to an idle or inactive user equipment, the serving gateway (SGW) entity may need to locate the idle or inactive user equipment by transmitting a downlink data notification (DDN) message—including a paging request—to the mobility management entity (MME) while buffering the Internet Protocol (IP) data packets. Upon reception of a downlink data notification (DDN) acknowledge message in response to the downlink data notification (DDN) message, the serving gateway (SGW) entity may forward the Internet Protocol (IP) data packets to the respective user equipment using at least one communication bearer.
As the number of user equipments under Long Term Evolution (LTE) coverage steadily increases, a relatively large number of service requests may be placed within relatively short time frames by a plurality of user equipments associated with the same mobility management entity (MME). Thus, a large number of downlink data notification (DDN) messages may be transmitted from the serving gateway (SGW) entity to the mobility management entity (MME) such that the mobility management entity (MME) may face an overload situation. For example, an overload situation may occur, when the memory required to process all incoming downlink data notification messages (including the paging requests) exceeds the available memory space at the mobility management entity (MME). In this case, a throttling mechanism may be initiated by the mobility management entity (MME) (upon reception of the downlink data notification (DDN) messages from a serving gateway (SGW) entity) in that the mobility management entity (MME) replies with a downlink data notification (DDN) acknowledge message—comprising a throttling request with throttling factor (TF) and throttling delay (TD)—to the serving gateway (SGW) entity in response to the downlink data notification (DDN) message. Subsequently, the serving gateway (SGW) entity may discard the transmission of further downlink data notification (DDN) messages to the mobility management entity (MME) in dependence of the throttling request included within the downlink data notification (DDN) acknowledge message.
However, the Internet Protocol (IP) data traffic is typically be prioritized according to the bearer allocation retention priority (ARP). This might lead to situations in which all communication bearers having the same bearer allocation retention priority (ARP) may be deactivated to free up resources resulting in an unwanted loss of important traffic and Internet Protocol (IP) data packets included in at least some of the deactivated communication bearers.